We have investigated the biochemical signals and gene expression induced by two distinct growth factors. Interleukin 2 which stimulates proliferation and differentiation of lymphoid cells and interleukin 3 which regulates myeloid cell growth and differentiation. We have shown interleukins to induce intracellular biochemical events such as: 1) activation of specific kinases; 2) ionic regulation; 3) cyclic nucleotide modulation; 4) phospholipid metabolism; 5) involvement of GTP-binding proteins; 6) synthesis of DNA polymerase regulatory nucleotide derivatives; 7) critical events associated with 40S ribosome function and 8) activation of topoisomerase and elongation factor activities, following growth factor interaction with high affinity receptors. In addition, we have identified at least five genes whose transcription is regulated by the respective growth factors. The laboratory has examined receptors common to the immune and central nervous system. We have characterized interleukin 1 (IL 1) receptors in rat brain, and the putative HTLV III/LAV T4+ receptor in human and primate brain. Synthetic peptides with homology to the HTLV III/LAV envelope protein have been shown to bind to the T4 antigen, to displace 125I gp120 envelope protein and to exhibit anti-viral infectivity activity against HTLV III/LAV in human T4+ lymphocytes.